The epithelial to mesenchymal transition (EMT) is the process through which cells in an epithelial layer detach from that layer and become migratory. EMT is one of the most common cellular behaviors, crucial for embryonic development and the metastasis of epithelial tumors. Little is known about the regulation of EMT in non-model organisms. A functional molecular examination of this process in a phylogenetic context will identify which aspects are core components and which are species-specific modifications. Cnidarians have a simple body plan and are considered "primitive" metazoans, making them useful for comparison to "higher" organisms such as the fruit fly, mouse and human. Gastrulation in the cnidarian Nematostella vectensis involves the ingression of cells into the interior of the embryo, a process that requires cells to undergo EMT. The objectives of this proposed research are to 1) characterize the cellular basis of gastrulation and EMT in N. vectensis, and 2) determine the function of N. vectensis orthologs of snail, beta-catenin, and cell-cell unction components likely to be involved in the control of EMT to reveal whether their roles are conserved in diploblastic organism.